Practical guidelines for setting up neurosurgery skills training cadaver laboratory in India.

Though the necessity of cadaver dissection is felt by the medical fraternity, and described as early as 600 BC, in India, there are no practical guidelines available in the world literature for setting up a basic cadaver dissection laboratory for neurosurgery skills training. Hands-on dissection practice on microscopic and endoscopic procedures is essential in technologically demanding modern neurosurgery training where ethical issues, cost constraints, medico-legal pitfalls, and resident duty time restrictions have resulted in lesser opportunities to learn. Collaboration of anatomy, forensic medicine, and neurosurgery is essential for development of a workflow of cadaver procurement, preservation, storage, dissection, and disposal along with setting up the guidelines for ethical and legal concerns.

PsychArray-Based Genome Wide Association Study of Suicidal Deaths in India.

Background: Suicide is a preventable but escalating global health crisis. Genome-wide association studies (GWAS) studies to date have been limited, and some are underpowered. In this study, we aimed to perform the PsychArray-based GWAS study to identify single nucleotide variations associated with suicide in the Indian population. Methods: We recruited unrelated subjects who died by suicide as cases (N = 313) and the non-suicidal deaths as controls (N = 294). The 607 samples were genotyped, including cases and controls using the Illumina Infinium PsychArray-24 BeadChip v1.3 Results: In our study, four single nucleotide polymorphisms (SNPs) crossed the threshold of significance level <1 × 10−5. One of them is intronic at Chromosome2:rs1901851 and three are intergenic at Chromosome12:rs3847911, Chromosome8:rs2941489, Chromosome8:rs1464092. At a significance level of 5 × 10−5, we found a few more SNPs, with the majority of them being intergenic variants. The associated genes were associated with various important functions ranging from cell signaling, GTP binding, GPCR binding, and transcription factor binding. Conclusions: The SNPs identified in our study were not reported earlier. To our best knowledge, this study is one of the first GWAS for suicide in the Indian population. The results indicate few novel SNPs that may be associated with suicide and require further investigation. Their clinical significance is to be studied in the future.

Nerve fibre morphometry with transmission electron microscopy: Application of the nucleator probe in ImageJ.

Stereology and semiautomated binary image histomorphometry are two common methods used for morphometry of nerve fibres. Nucleator probe can be used for the estimation of morphometric parameters like diameter, perimeter, area and volume of a structure that is approximately either a circle or a sphere. In this study, we estimated these parameters with the help of ImageJ software on calibrated transmission electron micrographs. We procured samples of the cochlear nerve (CN) during winter months, within 6-12 hours of death, to reduce post-mortem autolytic changes. The temporal bones containing the CN were fixed by immersion in chilled paraformaldehyde. After dissecting out from the petrous part of the temporal bone, the CN were osmicated and processed for embedding in resin. From the resin blocks, silver coloured (70 nm) ultrathin sections were cut and picked on 300-mesh copper grids, stained with uranyl acetate and lead citrate and viewed under Tecnai G2-20 transmission electron microscope. The transmission electron micrographs had scale bars embedded into them by the software at the time of imaging, and the morphometric parameters of randomly selected nerve fibres were measured using the ImageJ software. The ImageJ software could become a low-cost and dependable tool for nerve fibre morphometry.•Nucleator probe is used for the estimation of morphometric parameters like diameter, perimeter, area or volume•Morphometric parameters were estimated by the ImageJ software on calibrated transmission electron micrographs•The ImageJ software could become a low-cost and dependable tool for nerve fibre morphometry.

The ultrastructural study of human cochlear nerve at different ages.

Ultrastructural and molecular changes in the myelin of the cochlear nerve (CN) have been associated with decreased hearing-acuity with increasing age. But most of these are animal studies or with very few human samples. Hence, we studied the ultrastructure of the human CN at different ages. We obtained samples of CN from persons, who at the time of death belonged to young, middle or old age-groups; defined as ≤ 30, 31 to 50, and ≥ 51 years of age, respectively. These were processed for viewing under a transmission electron microscope (TEM). Morphology and morphometry were assessed after blinding the observer. Measurements of diameter (whole nerve fibre, axon), myelin thickness and calculation of G-ratio were made on calibrated images using ImageJ software. K-Means cluster analysis was performed based on total and inner nerve fibre area. Middle and old age CN showed degenerating axons, splitting of myelin sheath and myelin balloons. Between the middle and old age groups there was significant decrease in axon diameter (p<0.001), inner nerve fibre area (p<0.001), myelin thickness (p<0.001), nerve fibre diameter (p<0.001), and G-ratio (p<0.001). By clustering, we identified three distinct populations of myelinated nerve fibres: large, medium and small. The large fibres (by size), seen in the young, disappeared in the old age-group. We were unable to find any unmyelinated nerve fibres in this study. The morphological deterioration CN fibres may be a visible sign of molecular degeneration and contribute to decreased hearing-acuity.

Age-related changes in the number of cresyl-violet-stained, parvalbumin and NMDAR 2B expressing neurons in the human spiral ganglion.

Animal-studies associate age-related hearing loss (presbycusis) with decreasing number of spiral ganglion neurons (SGNs) in Rosenthal's canal (RC) of cochlea. The excitatory neurotransmitter for SGNs is glutamate (through its receptor NMDAR 2B), which can be neurotoxic through Ca2+ overload. Neurotoxicity is balanced by calcium-binding proteins (CBPs) like Parvalbumin (PV), which is the predominant CBP of the SGNs. To estimate the volume of the RC and total number of SGNs that are immunoreactive to PV and NMDAR 2B, we used unbiased stereology in 35 human cochleae derived from cadavers of persons from 2nd to 8th decade of life (subsequently statistically divided into two groups) and compared them to the total number of cresyl violet (CV) stained SGNs. We also estimated the volume of individual neurons and their nuclei. Regression analysis was made on estimated parameters against age. Hierarchical-cluster analysis was done on the neuronal against neuronal nuclear volumes.The average volume of the RC did not change with increasing age (p = 0.4115). The total number of SGNs (CV-stained and those separately expressing PV and NMDAR 2B) significantly decreased with age (p < 0.001). We identified three distinct populations of neurons on the basis of their volumes among SGNs. Thus, there is significant age-related decline in the total number of SGNs, which starts early in life. It may be due to ambient noise and inadequate neutralisation of excitotoxicity.

Morphological and neurochemical changes in GABAergic neurons of the aging human inferior colliculus.

It is well known that quality of hearing decreases with increasing age due to changes in the peripheral or central auditory pathway. Along with the decrease in the number of neurons the neurotransmitter profile is also affected in the various parts of the auditory system. Particularly, changes in the inhibitory neurons in the inferior colliculus (IC) are known to affect quality of hearing with aging. To date, there is no information about the status of the inhibitory neurotransmitter GABA in the human IC during aging. We have collected and processed inferior colliculi of persons aged 11-97 years at the time of death for morphometry and immunohistochemical expression of glutamic acid decarboxylase (GAD67) and parvalbumin. We used unbiased stereology to estimate the number of cresyl-violet and immunostained neurons. Quantitative real-time PCR was used to measure the relative expression of the GAD67 mRNA. We found that the number of total, GABAergic and PV-positive neurons significantly decreased with increasing age (p < 0.05). The proportion of GAD67-ir neurons to total number of neurons was also negatively associated with increasing age (p = 0.004), but there was no change observed in the proportion of PV-ir neurons relative to GABAergic neurons (p = 0.25). Further, the fold change in the levels of GAD67 mRNA was negatively correlated to age (p = 0.024). We conclude that the poorer quality of hearing with increasing age may be due to decreased expression of inhibitory neurotransmitters and the decline in the number of inhibitory neurons in the IC.

Skin suicide note written in mehndi (henna).

Suicide messages on the skin are rare. Until now, in all reported cases, the writing tool used by the victims has been a pen. We report a suicide case by hanging in which the victim had written a note on her palm in mehndi, or henna, at a wedding ceremony three days before the fatal act. The note was discovered at autopsy.

A case of accidental fatal aluminum phosphide poisoning involving humans and dogs.

Aluminum phosphide is one of the commonest poisons encountered in agricultural areas, and manner of death in the victims is often suicidal and rarely homicidal or accidental. This paper presents an unusual case, where two humans (owner and housemaid) and eight dogs were found dead in the morning hours inside a room of a house, used as shelter for stray dogs. There was allegation by the son of the owner that his father had been killed. Crime scene visit by forensic pathologists helped to collect vital evidence. Autopsies of both the human victims and the dogs were conducted. Toxicological analysis of viscera, vomitus, leftover food, and chemical container at the crime scene tested positive for aluminum phosphide. The cause of death in both humans and dogs was aluminum phosphide poisoning. Investigation by police and the forensic approach to the case helped in ascertaining the manner of death, which was accidental.